I have noticed that mangaupdates considers mass upload by a group as 1 release. Like if a group releases a lot of chaps of a manga at the same time like for eg: 10 chaps it'll show it as 1-10 released and it's counted as 1 release where as the total no of releases are 10. Just check any groups that do mass uploads, you'll find that comparisons differ. Mangaupdates have significantly lower numbers than mangadex. Whereas mangadex always shows the correct if the group always releases their chaps there. I checked out with a group seems like I was right.

This isn't a bug but a rule at mangaupdates.
Also it would be silly to list each chapter as individual release if they released it at the same time.

I think the differentiation here is mangadex specifically lists # of chapters on the group page, whereas mangaupdates lists # of releases, there's a subtle difference here.

In theory, this would mean if you release v2 of a chapter at a later time, it would count as another release on mangaupdates, but # of chapters would remain the same on mangadex, since v2 would replace the existing chapter on mangadex

Everyone above is correct. We will not be changing the way we count "releases"

A just ruler amongst tyrants